I am, moreover, in the same position when I enter into the exceptional state and reflect on my own thinking. I can never observe my present thinking; I can only subsequently take my experiences of my thinking process as the object of fresh thinking If I wanted to watch my present thinking, I should have to split myself into two persons, one to think, the other to observe this thinking. But this I cannot do. I can only accomplish it in two separate acts. The thinking to be observed is never that in which I am actually engaged, but another one. Whether, for this purpose, I make observations of my own former thinking, or follow the thinking process of another person, or finally, as in the example of the motions of the billiard balls, assume an imaginary thinking process, is immaterial.
 There are two things which are incompatible with one another: productive activity and the simultaneous contemplation of it. This is recognized even in Genesis (1, 31). Here God creates the world in the first six days, and only when it is there is any contemplation of it possible: "And God saw everything that he had made and, behold, it was very good." The same applies to our thinking. It must be there first, if we would observe it.